GRS 2002: German Radar Symposium in Bonn, Germany

The German Radar Symposium (GRS 2002), organized jointly by the German Institute of Navigation (DGON) and by the Information Technology Society (VDE-ITG), attracted wide interest in the international radar community. It was held from September 3-5, 2002, in Bonn, the former capital city of Germany. The GRS 2002 programme covered a large scale of important radar topics. All classical topics like air traffic control, CFAR, antenna technology, signal processing and simulation papers have been presented and new results were demonstrated. These topics were combined with new applications like meteorology, subsurface, and automotive to underline the increase of interest in radar technology. Phased array antennas are the key elements of high performance multi-function radar systems which are studied all over the world. SAR and ISAR are, nowadays, essential radar techniques for civil and military observation and monitoring.     

Decision Cells for Positional Radar Identification of Satellites

There is a problem in deciding whether a radar observation of an object in outer space is of a known catalogued satellite or of a newly launched satellite. With some radar systems joint or dumbell radar images of two satellites cause occasional confusion, and appropriate decision theory for this situation is derived. Decision theory for the individual image is given in an appendix.     

A visionary look at aviation surveillance systems

The FAA's future aviation surveillance systems fall into four categories: Automatic Dependent Surveillance (ADS) will be used in the oceanic environment; ADS-Broadcast (ADS-B) will be used in the domestic en route environment; ADS-B will be used with a secondary radar backup in the terminal area; and ADS-B will be used with primary radar backup within the Airport Surface Traffic Automation (ASTA) system on the airport's surface environment. Two other systems introduced in this paper are Cockpit Display of Traffic Information (CDTI) and Traffic Advisory and Collision Avoidance System (TCAS). All these systems will use navigational signals emitted by the Global Positioning System (GPS) constellation of satellites     

Rate-constrained target detection

Given little or no a priori information, a real world detection system has the task of allocating limited resources. Often these resources are themselves detection systems that operate at a slower rate, for example a tracker following a radar. Detection systems that are described by serial multiple decision points with each decision device assumed to be more reliable but slower than the device preceding it are considered. It is shown that because of the rate constraint the Neyman-Pearson criterion is suboptimum. An optimum rate-constraint test is developed which has the same likelihood ratio form as the Neyman-Pearson test. A strategy for controlling multiple-point detection sequences is developed that depends only on local information and is shown to be optimum under fairly broad conditions. The strategy can be implemented in practical systems, since it depends on the hit rate which is both controllable and observable. This approach to decision-making has applications in many fields and shows a promise as both an analysis and design tool     

Development of airborne moving target radar for long range surveillance

The following topics are discussed in the context of the development of an airborne moving target radar for long range surveillance: US Navy long range shipborne radar; Cadillac I airborne early warning (AEW) radar; Cadillac II airborne early warning (AEW) radar; airborne moving target indicating (AMTI) radar; related post-war radar activities; and the invention of the displaced center antenna. Among the topics studied is the use of a monopulse antenna in an MTI radar to remove the degradation of the MTI caused by rapid scanning of the antenna. A method of using a monopulse antenna for motion compensation in airborne MTI is discussed.<>     

First spaceborne demonstration of BeiDou-3 signals for GNSS reflectometry from CYGNSS constellation

The full constellation of Chinese Global Navigation Satellite System (GNSS) BeiDou-3 has been deployed completely and started fully operational service. In addition to providing global Positioning, Navigation and Timing (PNT) services, the BeiDou-3 satellites transmissions can also be used as the sources of illumination for Earth Observation (EO) with a bistatic radar configuration. This innovative EO concept, known as GNSS reflectometry (GNSS-R), allows to measure the Earth surface characteristics at high resolution via the reflected L-band radar signals collected by a constellation of small, low cost and low Earth orbiting satellites. For the first time in orbit, earth reflected BeiDou-3 signal has been detected from the limited sets of raw data collected by the NASA’s Cyclone GNSS (CYGNSS) constellation. The feasibility of spaceborne BeiDou-3 reflections on two typical applications, including sea surface wind and flooding inundation detection, has been demonstrated. The methodology and results give new strength to the prospect of new spaceborne GNSS-R instruments and missions, which can make multi-GNSS reflectometry observations available to better capture rapidly changing weather systems at better spatio-temporal scales.     

Statistics of Focused and Defocused Radar Maps

Coherent high-resolution synthetic-aperture radar systems achieve their range resolution by pulse compression and azimuth resolution by compression of naturally generated FM coding due to Doppler shifts as the aircraft flies by the target. If the data is left unprocessed, it is, in effect, a defocused map of the terrain. As such, it should exhibit less dynamic range than if the data is compressed. This paper describes an experimental study to verify the above conjecture. The results of this study indicate that if dynamic range of the data link is a problem, the radar data should be transmitted in its unprocessed form. This might very well be the case for planetary mapping by means of satellites.     

Space-borne technology and inversion techniques for radar

This presents recent progress of the state-of-the-art of space-borne radar technology in case of either earth-orbiting or planetary-orbiting satellites and space probes, respectively. In addition to that, recent progress is also discussed concerning specific inversion techniques to evaluate radar measurements; i.e., the art of deriving the relevant physical quantities to be determined such as terrain and depth profiles for planetary surface and/or subsurface structures ((3D)-profiles) from radar data measured depending on signal frequency, aspect angle, polarization, etc., as a function of time.     

Range Instrumentation Radars

The history of range instrumentation radars begins at the end of World War 11, with the SCR-584 radar. Since then, the use of instrumentation radars on ranges all over the globe has expanded greatly to gather metric performance data on aircraft, projectiles, missiles, and satellites. In this paper, key subsystem-level and system-level developments during the past decade are reviewed, including pulse-Doppler, digital range systems, calibration techniques, computer usage, and dualfrequency systems. Recently developed instrumentation radars from domestic and foreign sources are described as are three unique high-power large-aperture systems used for satellite and ballisticmissile measurements. The paper concludes by examining the likely requirements for instrumentation radars of the future.     

MIMO radar: snake oil or good idea?

MIMO communication is theoretically superior to conventional communication under certain conditions, and MIMO communication also appears to be practical and cost-effective in the real world for some applications. It is natural to suppose that the same is true for MIMO radar, but the situation is not so clear. Researchers claim many advantages of MIMO radar relative to phased array radars (e.g., better detection performance, better angular resolution, better angular measurement accuracy, improved robustness against RFI, ECM, multipath, etc.). We will evaluate such assertions from a system engineering viewpoint. In particular, there are serious trade-offs of MIMO vs. phased array radars relative to cost, system complexity, and risk considering numerous real world effects that are not included in most theoretical analyses. Moreover, in many cases one can achieve essentially the same radar system improvement with phased array radars using simpler, less expensive, and less risky algorithms. We evaluate roughly a dozen asserted advantages of MIMO radar relative to phased arrays.     

World Space Congress: a vision quest

The World Space Congress (WSC) in October, 2002, brought together luminaries, aerospace engineers, students, and scientists to discuss strategies for reviving the world's space agency. WSC lectures and plenary sessions focused on future research in space. Among topics discussed are the use of the Hubble Space Telescope to scan for habitable planets and obtain data about the beginning of the universe, new weather satellites, planetary protection from comets or asteroids, exploration and establishment of colonies on the Moon and Mars, medical advances, the role of space exploration in the world economy.     

Geostationary Satellite Navigation Systems

The concept of position determination using geostationary satellites as an alternative to the global positioning system (GPS) is studied. The advantage of a geostationary system is that only three, or at most four, satellites are required to cover the continental United States. A total of twelve satellites are sufficient for global coverage (excluding polar regions), or eight if only longitude and latitude, but not altitude, are measured. The system involves the determination of the range to either four geostationary satellites or, if the altitude is not measured, three geostationary satellites. The accuracy of the proposed systems are evaluated to obtain the rms error associated with position determination, and the concept for the implementation of measurements required by the systems is presented. The accuracy of the systems are adequate for civilian use in the continental United States; however, there is a degradation in accuracy as the location of the user approaches the equator.     

Sensor systems signal processing platform

A field programmable gate array-based computing platform for high-speed sensors such as short-range radars is presented. The circuit performs necessary A/D conversions, raw data stream compression and target detection, and constructs a message structure suitable for external displays. In the prototype, USB is the connecting path to a laptop computer. An elementary pulse radar is utilized as an application example. An application interest would be in collision avoidance systems. Observed data transfer rates with real radar input signals were 36 Mbytes/s when typical target detection algorithms were applied.     

A hardware signal processing platform for sensor systems

A field programmable gate array-based computing platform for high-speed sensors such as short-range radars is presented. The circuit performs necessary A/D conversions, raw data stream compression and target detection, and constructs a message structure suitable for external displays. In the prototype, USB is the connecting path to a laptop computer. An elementary pulse radar is utilized as an application example. An application interest would be in collision avoidance systems. Observed data transfer rates with real radar input signals were 36 Mbytes/s when typical target detection algorithms were applied.     

Nostradamus: An OTH Radar

ONERA, funded by the French Ministry of Defence has conducted the realization and experimentations of the Doppler Skywave OTH radar called NOSTRADAMUS. One of the main characteristics of Skywave OTH radar is the dependence to the ionosphere for successful operation. The use of the HF band allows Skywave OTH radar to bounce radio waves from the ionosphere, receiving tiny signals back from reflecting surfaces as the sea, islands, ships and aircraft. The knowledge of the behavior of the ionosphere in a real time configuration is of primary importance because it influences on the choice of frequencies. Radars systems require developing a real-time frequency management system (FMS) using prediction program or measurements supplied by vertical or oblique sounders. The French OTH radar concept has been developed and implemented so that the radar could be completely autonomous with respect to others "ionospheric information providers." This paper presents the NOSTRADAMUS system, the frequency management system, and shows some results obtained during the past years     

Scanning Spaceborne Synthetic Aperture Radar with Integrated Radiometer

Spaceborne synthetic aperture radar systems are severely constrained to a narrow swath by ambiguity limitations. Here a vertically scanned-beam synthetic aperture system (SCANSAR) is proposed as a solution to this problem. The potential length of synthetic aperture must be shared between beam positions, so the along-track resolution is poorer; a direct tradeoff exists between resolution and swath width. The length of the real aperture is independently traded against the number of scanning positions. Design curves and equations are presented for spaceborne SCANSARs for altitudes between 400 and 1400 km and inner angles of incidence between 20° and 40°. When the real antenna is approximately square, it may also be used for a microwave radiometer. The combined radiometer and synthetic-aperture (RADISAR) should be useful for those applications where the poorer resolution of the radiometer is useful for some purposes, but the finer resolution of the radar is needed for others.     

Sets of One and Higher Dimensional Welti Codes and Complementary Codes

A Welti code is a binary sequence with an impulse-like autocorrelation function. A set of such codes may possess vanishing cross-correlation functions. The elements of Welti codes must be members of a set of at least two orthogonal vectors or subcodes. First, methods for synthesizing sets of one-dimensional Welti codes with vanishing cross-correlation functions, and conditions upon their existence are discussed. Then, construction methods of sets of two and higher dimensional Welti codes are presented. Based on these constructions, further sets of mutually orthogonal complementary codes in one or more dimensions can be derived. The use of such signals relates to various topics such as communication, radar and navigation systems, measuring and identification in one or higher dimensional systems, synchronization and spatial alignment, or coded aperture imaging.     

基于UPPAAL软件的实时系统设计研究

UPPAAL是丹麦Aalborg和瑞士Uppsala大学联合开发,具有世界先进水平的实时系统模拟,校核的软件,基于对实时系统严密逻辑,真实时间的抽象,而构建时间状态机动态模型网络,模拟,校核系统,检测潜在失败,保证设计可靠性,雷达传感器内存接口实时系统是航天雷达系统重要组成部分。本文UPPAAL软件对此系统精确的动态数学模型,模拟,校核系统,覆盖各设计阶段,保证实时系统设计可靠性。     

小型卫星的固体火箭推进系统

简述小型卫星热及对推进系统的选择，讨论了各国小型运载火箭的固体推进系统，分析了它们的特点和技术状况。     

Analysis of queuing behavior of automatic ESM systems

Radar electronic support measures (ESM) systems detect active emitters in a given area and determine their identities and bearings. The high arrival rate of radar pulses in dense emitter environments demands fast automatic processing of arriving pulses so that the ESM system can fulfill its functions properly in real time. Yet, the performance analysis of automatic ESM system in real life Is difficult since both pulse arrivals and widths can be specified only probabilistically. The success of queuing theory in many applications such as computer communication networks and flow-control has encouraged designers to utilize queuing theory in qualifying and judging the performance of automatic ESM systems in dense emitter environments. The queuing behavior of these systems is analytically evaluated under different service disciplines and elaborate computer simulations validate the results. The analysis involves statistical modeling of arrival and departure processes as well as distribution of service times. It permits estimating the blocking probability due to high arrival rates of intercepted radar pulses or due to limited speed of the deinterleaver processor. Queuing analysis is shown to be quite useful to quantitatively assess tradeoffs in ESM systems design